A communication system may provide a subscriber with a fixed line connection or a wireless connection for communication, such as for voice or data communication. An example of the fixed line systems is the public switched telephone network (PSTN). An example of a wireless communication system is the public land mobile network (PLMN) and another example is a satellite based mobile communication system. The wireless communication occurs typically via a radio frequency connection between the station of the subscriber and at least one network element of the communications system. Communication within the network is typically, but not necessarily, handled by fixed line connections between the various network elements. Communication may also be transmitted in a system comprising one or more data networks. An example of this is the voice over IP (Internet Protocol) arrangement enabling voice call over a packet switched data network. The communication system may also employ a combination of wireless, fixed line and/or data network communication for a connection between two terminals. The term “connection” is intended to refer to all types of communication between two signalling points, such as a user terminal. The communication via the connection may be, for example, in the form of a voice call or a multimedia call or a data communication session.
A communication system typically operates in accordance with a standard or specification which sets out what the various elements of the network are permitted to do and how that should be achieved. For example, the standard or specification may define whether the user, or more precisely, user equipment or terminal is provided with circuit switched and/or packet switched service. The standard or specification may also define the various communication protocols and/or parameters which shall be used for the connection. In other words, the standards and/or specifications define the “rules” on which the communication and various associated functions can be based on. The various functions that are based on these rules may be arranged in predefined layers, e.g. to so called protocol stacks.
In addition to basic voice and data services, the users of the subscriber terminals (such as fixed line telephones, data processing devices or PLMN mobile stations) may be provided with additional or advanced services. These can be defined as functions providing various sophisticated services or value-added services to the subscribers, for instance by means of software and/or hardware implementations provided in one or several nodes of the communication system. The additional services requested and subsequently invoked for a connection typically require control of at least one of the call management functions (e.g. routing, charging, duration, provision of connection or user related data and so on).
The additional services can be implemented by means of a functionality that is often referred to as intelligent network (IN). The term “intelligent network” was introduced by the BELLCORE organisation (U.S.A.) in the mid eighties. The intelligent network (IN) concept was developed in order to increase the flexibility and competitiveness of the telecommunication network architecture. Even though the initial IN architectures were developed to implement only certain specific services, for example service number, the current IN solutions provide the communication network operators with a possibility to implement new, powerful services in their networks in a fast and cost-effective manner.
The basic principles and operation of the IN applications are well known, and therefore they are not described herein in more detail. It is sufficient to note that in general the IN architecture comprises a (service) switching point (SSP) for triggering a call to the IN services and a (service) control point (SCP) for providing the service. The SSP and the SCP functions may be integrated in a service switching and control point (SSCP). A more detailed description of the general IN concept can be found e.g. from the recommendations by the International Telecommunications Union (ITU-T), such as IN Capability Set CS-1 published in 1993. The IN concept can be implement in the fixed land line networks, such as the public switched telephone network (PSTN), or the wireless radio communication networks, such as the public land mobile network (PLMN). Customised applications for mobile network enhanced logic (CAMEL) application part (CAP) protocol may be used in the SCP of a PLMN system for the provision of the service logic.
A service available for the subscribers is so called prepaid service. In a prepaid service arrangement the user of a terminal, such as a mobile station, may purchase beforehand a certain predefined amount of calling time or other service time. The prepaid amount will be referred to as balance. The balance may be purchased in any appropriate manner, e.g. by purchasing calling cards or vouchers, by means of a bank transfer, and so on. The balance will be stored in a prepayment account implemented by means of the intelligent network. The user may then make calls against his/hers account until the balance in the prepayment account runs out. It may also be possible for the user to reload more balance in the account, or the user may simply purchase a new prepaid account after the balance in the previous account has run out. Although the prepaid account holders can be identified, it is also possible that the prepaid accounts are anonymous, i.e. the operator does not necessarily know the identity of the owner of the account.
In the prepayment service a call may be charged by deducting (decrementing) during the call the balance on the account based on a calculated charge parameter that will referred to herein as a call charge. The call charge may be calculated based on a charging component. The call charge may be calculated by means of the intelligent network based on information that associates with the chargeable resource of the communication system. In some application the calculation is accomplished by means of a controller of the network, such as the mobile switching center or a specific billing centre. For example, in a GSM standard (Global System for Mobile communications) the call charge component may be calculated based on charging components that are referred to as e-parameters or main charging zone (MCZ) parameters. It should be noted that other standards may employ differently named parameters for the same purposes. The charging component for a call is typically obtained from a controller of the systems, such as from a mobile switching center (MSC) of the GSM system, for the calculation of the call charge, i.e. the calculation of the amount that is to be deducted from the balance.
The operator of a network may want to offer free connection time or other service time for the subscribers to the network. The operator may wish to do so e.g. on selected days or selected times of a day. If the operator wants to offer free airtime for those mobile subscribers that use prepaid services, this may be accomplished at the mobile network by waiving any airtime charges off. However, if the call is made to a terminal connected to another network, e.g. to a terminal connected to a PSTN, the operator of the originating network may become liable for clearing charges later on for the use of the resources of said other network regardless the nature of the charging (post paid or prepaid charging). Clearing of call charges incurred in the other networks usually takes few days to accomplish. The operators of the originating network may however, wish to charge also these charges from the subscriber who originated the call even if the call was made by a prepaid subscriber.
To be able to establish at once the total call charge for call made using the chargeable resources of at least two networks, the intelligent network (IN) of the originating network should know the charging components from all networks involved. However, the controller of the originating or first network (such as the MSC) does not necessarily get this charging information from the destination or the second network in all current charging applications. This may cause problems especially when the originating terminal pays for the connection by means of a prepayment service, since the system should be able to deduct the charges during the connection from the balance associated with the originating terminal.
The above situation is clarified by means of the following example. Although the mobile switching center (MSC) of a PLMN system may obtain the charging component that is associated with the charges in the PLMN system, the mobile switching center does not necessarily receive all information required for the charging from the PSTN e.g. via ISUP (ISDN User part) signalling. If the operator of the PSTN does not want to transfer charging messages via the ISUP signalling to other networks, such as to the PLMN, then the calculation of components need to be generated in the PSTN where the charges incurred. That is, the required charging definitions have to be precalculated in the home PSTN network if the charging information is not transferred to other networks e.g. by means of the ISUP. The charges need also to be cleared later on between the operators of the two networks. In the post paid charging arrangements this is usually not a problem since the cleared charges can be added to the bill of the PLMN subscriber later on in a billing centre of the PLMN operator. However, this is not possible with the subscribers to the prepaid services, as their charging should occur immediately during the connection.
Although it may be possible to provide the controller of a network, such as the MSC of a PLMN, with information regarding the use of resources in all networks, the controller cannot calculate these different components separately. In conventional post-payment arrangements this is not usually a problem since the charges for a call can be sorted out later on. However, in the prepayment arrangements the services have to be charged immediately. The services also have to be charged in their entirety during the call. The controller may not be made aware of all of the charging components and/or the controller may not be able to calculate all of the needed components and/or to calculate the components separately. Therefore, although the originating network may be able to produce some kind of estimate of the charges for the prepaid subscribers, the charging of the pre-paid subscribers may still be inaccurate.
A problematic situation may also occur when more than one independently operating charging model is used for a call from a common termination point. Different call charge control features used in the different charging and tariff schemes may be in conflict with each other and/or may not interact in a proper manner. The different charging models and/or the charging components produced by the different models may not even be used for a single connection.
For example, in some cellular communication systems the mobile station originated call tariffs have two different components. The exemplifying two components will be referred to as ‘an Airtime Charge’ and ‘a PSTN charge’. These two components are first computed independently and subsequently summed together e.g. in the post payment billing centre to obtain the total call charge. The Airtime rate may depend on various parameters, such as the time of day, the subscriber category, the rate plan to which the subscriber has signed on, the destination of the call and so on. The PSTN component may also depend on various factors such as the time of day, the distance to the called destination, subscriber profile and so on. The Airtime and PSTN components may increment in different time units. For example, the Airtime component may increment once per minute while the PSTN component may increase every 30 seconds. It is also possible that one of the components is incremented in units that do not dependent on time (e.g. in pulses). The tariff structures of the two charging models may be substantially different from each other.
A connection set-up procedure for establishing a connection between two terminals may be based on use of a originating state model. One possible originating state model is the Originating Basic Call State Model (OBCSM) of the Intelligent Network Application Part (INAP) protocol suite. The INAP OBCSM is a typical example of the first (originating) phase of call set-up procedures. However, the inventors have found that the controller of the originating network cannot calculate independently the two or more charging components at the same time in a same originating state model. For example, the MSC is not enabled to handle simultaneously the two charging components in the same protocol (e.g. INAP or CAP) and to report them to the SCP independently from each other. Thus the service control point (SCP) may receive information of one charging component only since only one protocol can be used at the MSC. On the other hand, the inventors have also found that the SCP cannot proceed to calculate more than one of the charging components based on a single triggering at the service switching point (SSP).